Megachu!

Based on an adult game by Front Wing.
Kousuke is a happy-go-lucky college student who suffers from a disturbing reoccurring nightmare where he becomes a rampaging sex demon! He’s at a loss to understand the significance of his dream as he goes about playing his favorite video games. One day a beautiful goddess named Fauna appears before him, not to grant wishes, but vows to destroy him! When Kousuke discovers he is possessed by a powerful evil demon, the battle begins!
(Source: Media Blasters)